Typhoon Dolphin, a "very strong" storm with maximum wind speeds of 162km/h (101mph), has caused power outages in at least 44,000 buildings and injured five people after striking Japan's Okinawa island on Saturday. The typhoon forced the closure of Naha International Airport, cancelling flights to and from the main airport, and resulted in numerous accounts of trees being toppled and a car overturned in Nago city, Okinawa. Authorities in China have raised a coastal typhoon alert to its highest level, shutting ports, schools, and halting port and ferry services ahead of Dolphin's expected landfall on China's eastern coast late on Sunday or early Monday. Japan's meteorological agency reported that the main areas affected by Typhoon Dolphin are the islands of Okinawa and Amami in the far south-west of the country, with five elderly people suffering non-life-threatening injuries. This year is a strong El Niño year, which experts say can intensify typhoons. In an average year, around three cyclones reaching tropical storm strength in the western Pacific typically make landfall in Japan, with some classified as typhoons. A typhoon is a term used for storms that form in the north-west Pacific, whereas a hurricane is the term used for storms that form in the Atlantic or eastern Pacific.